CRISPR-Cas9 and the future of gene editing and genetic counseling

CRISPR-Cas9 gene editing technology is opening a world of possibilities for the treatment and prevention of human disease and genetic abnormalities. It’s also opening a can of ethical worms regarding what the limitations should be—particularly with respect to altering human embryos. This blog looks at the benefits and complications of CRISPR-Cas9 through the eyes of a genetic counselor.

There have been several stories in the news recently about human embryo gene editing: both good and bad. The development of CRISPR-Cas9 technology, one of the most recent and celebrated gene editing techniques, has resulted in a series of experiments using human embryos that have brought the ethics of gene editing to the fore.

It started in 2015 when a team of Chinese researchers used a gene editing technique called CRISPR-Cas9 to edit the genes of human embryos in an effort to ‘remove’ the part of the DNA that was responsible for a fatal blood disorder (β-thalassaemia) (published in Protein & Cell).

More recently, in August of 2017, an international team of researchers released a paper in Nature in which they manipulated human embryos using CRISPR-Cas to ascertain whether or not this technique could be successfully used in the removal of a fatal genetic mutation. Research on gene editing (especially germ line editing involving human embryos) has situated researchers in the middle of an ethical quagmire.

A review published in Human Genomics by Capps et al. briefly examined the ethical issues surrounding this new technology in their paper wherein they examined the ethical complications of such research but the need to balance this with the greater good of human health and medical progress.

Whether someone is for or against genetic editing, what’s clear is that researchers are eager to refine and perfect gene editing technology given the seemingly limitless potential uses that could benefit humanity in countless ways. Reliable, accurate gene editing could revolutionize the way people think about their decision to have offspring or the fact that they have tested positive for a genetic mutation linked with a specific disease or disorder.

Given this, what do these developments mean to professionals working and advising the public in fields like genetic counseling?

I spoke with Sharon Chen (MS, CGC), a Genetic Counselor at Northwell Health Division of Medical Genetics & Genomics. When asked about CRISPR-Cas9 and gene editing technology, she stated that she believes this technology is here to stay and the big question is: how is this going to be used and what are the potential side effects?

What would the widespread access to CRISPR-Cas9 mean for a genetic counselor?

The majority of the patients Sharon counsels are expectant parents or couples that are looking to get pregnant who have been identified as at risk. Sharon considers that gene editing (especially germ line editing) could have a major impact on the options counselors would be able to provide. Currently, couples at risk are provided rather limited options: they can find out in advance if the pregnancy is impacted (in utero testing) and make an informed determination about keeping or terminating the pregnancy or they can do IVF/PGD (in-vitro fertilization/pre-implantation genetic diagnosis) in which each embryo is tested and only the unaffected embryos are then implanted. If gene editing technology, such as CRISPR-Cas9, becomes more widely available then counselors have a host of new options. Furthermore, Sharon believes that “if gene editing were available, then we could then talk about a third option: ‘curing’ the baby. This could mean having the baby first and then curing it, or even curing it in utero.”

The Risks of Gene Editing Technology in the Real World

However, as others have also noted, introducing this technology is not without its risks. “There’s always the risk of unintended consequences since the technology is not yet perfect: they might edit the gene responsible for Tay-Sachs and in the process mutate the gene for tumor suppression, introducing an entirely new medical challenge.” There’s also the possibility, for couples that go the IVF route, that the ‘fixed’ embryo ends up not actually being fixed (or with a new unintended genetic mutations, which has medical consequences)—leaving them back where they started.

Important ethical considerations cannot be ignored with this kind of medical intervention. Sharon notes that while this technology could be used to do so much good, there’s a “slippery slope” and it’s easy to imagine an emergence in wanting to make non-essential genetic edits to embryos (such as selecting for eye color, height, etc.). With no international agreement in the medical or legislative community outlining the ‘rules’ for the use of gene editing, it’s a technology that could theoretically be used to create so-called “designer babies.” Sharon points out that part of the difficulty is that researchers in China have already done things with this technology that have not been permitted in the U.S., so the lack of international guidelines for a powerful technology such as this is problematic.

Lastly, and possibly the most disconcerting consideration Sharon raises is the likelihood that gene editing options will only be available to those who can afford it. “As it is already, IVF is incredibly expensive (around $10,000 per treatment) and isn’t covered by most insurance companies. Factor PGD into it, and you’re looking at a lot more money” she noted. If gene editing were added into these costs, they could become astronomical, limiting access to only the very wealthy.

All that being said, Sharon is hopeful that the technology continues to improve and that researchers and medical professionals from around the world can work together to establish firm guidelines for use in humans and there comes a time when she is able to provide more options to the couples she counsels.

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